If you’ve ever looked at a burgeoning allotment site crammed with serried ranks of fabulous veggies and wondered ‘how did they do that?’, the answer is probably crop rotation.

It’s a system that’s as old as food cultivation itself, and can be used in raised beds as well as larger allotments and vegetable gardens.

Crop rotation benefits the soil and plants in three main ways:

It helps maintain and balance soil fertility as different crops take different nutrients from the soil.

It can help control weeds, as crops such as potatoes and squashes have dense foliage that cover the soil.

It helps prevents pests and diseases from building up in the soil.

It isn’t difficult to set up a three- or four-year cycle of crops. Start by organising what you plan to grow into groups – brassicas (cabbage, cauliflower, sprouts, kohlrabi, swedes and turnips), legumes (peas and beans), onions, shallots and garlic, the potato family (which includes tomatoes, peppers and aubergines) and root vegetables (carrots, parsnips, celery, celeriac, parsley and beetroot).

When you sow, onions and roots can go together and if you are sticking to a three-year system, legumes can be planted with them as well. Below I show you a simple four-year rotation. If growing in containers, wash the pots at the end of each season to avoid transmitting pests and disease, and plant up in fresh compost next year.

What can go where in a simple four-year crop rotation

Year one

Section one: Legumes

Section two: Brassicas

Section three: Potatoes

Section four: Onions and roots

Year two

Section one: Brassicas

Section two: Potatoes

Section three: Onions and roots

Section four: Legumes

Year three

Section one: Potatoes

Section two: Onions and roots

Section three: Legumes

Section four: Brassicas

Year four

Section one: Onions and roots

Section two: Legumes

Section three: Brassicas

Section four: Potatoes

Some common problems

Blight is a fungal disease that affects tomatoes and potatoes Once it arrives, there is little defence against it.

Bean rust affected my broad beans, although I still had a decent crop. Improve airflow around the plants to reduce the risk of it developing.

Blackfly and aphids can seriously weaken plants. Squash small gatherings before they become infestations.

Someone remind me to net my brassicas this year! Last year’s crop was turned to ribbons by cabbage white caterpillars.